Is this proof your DNA holds the secret to weight loss?

This is the scientific breakthrough that promises to take the guesswork out of dieting.

A simple swab is taken from the inside of your cheek and posted to a laboratory. There, scientists analyse your DNA, examining your genetic make-up. Most crucial are genes that influence body size and weight, fat processing and storage, ability to lose weight and maintain it, plus the likelihood of developing high cholesterol.

For example, around one in five Europeans carry a gene making them more likely to eat high-carbohydrate food. Another gene, called MTIF3, has been linked to increased body size and also to the regaining of weight after dieting. And a variant of the FTO gene, which controls appetite, has been dubbed the ‘fat gene’, because it’s linked to impulse eating and weight gain.

Armed with this information, experts formulate a diet tailored to your genetic make-up — recommending meal plans, portion sizes and even exercise regimes. There are 180 variations of meal plans based on common regimes including high protein, low carb, high fat, high Omega-3 and Mediterranean diets, and may be customised depending on how the body reacts to certain foods and whether the goal is to lose or maintain weight.

Six women shared their experience of following a genetically tailored diet regime based on their DNA test results. Emma Bytheway, 38, (pictured before) was advised to follow a low calorie, omega-3 rich diet for four months

Some studies suggest a genetically tailored regime could increase weight loss by as much as 40 per cent, while Harvard researchers found ‘preliminary but promising’ evidence for the trend.

But many scientists remain sceptical. ‘It’s true we all have gene variants that determine how we metabolise different components of food,’ says Professor Bill Newman, who studies genetics at Manchester University.

‘But our knowledge of these factors is limited. Even more limited is evidence that applying certain diets in the light of having a specific profile of genetic variants is of any benefit.’

So, is DNA dieting a gimmick or a breakthrough? We asked seven serial dieters to take a £59 test offered by myDNA, available online or at Lloyds Pharmacy, which gives you a diet plan tailored to your results.

After four months, how have they got on?

Low calorie, omega-3 rich

Weight loss: 1st

Emma Bytheway, 38, is a training advisor and lives in Staffordshire. She is a single mum of two boys aged nine and five.

The DNA test results terrified me. I discovered I have a 40 per cent chance of coronary problems — which killed both my dad and grandmother — before I’m 45, if I don’t make drastic changes to my diet and lifestyle.

Emma Bytheway, 38, (pictured) after from Staffordshire went from 12st to 11st

In the past, I’ve followed crash diets and lost the weight but I always pile it on very quickly and this could be because I have an active FTO — the ‘fat gene’ — which can increase appetite. But now that I know I’m more susceptible to weight gain, I’m much more careful and as a result, I’m leaner and happier than I was four months ago.

My new diet is high protein to keep me fuller for longer with plenty of good fats — omega-3 — which meant lots of fish, nuts and seeds and I feel that I’m creating habits for life. I’ve stuck rigidly to the diet with only a few treats once a week, such as a meal out or a glass or two of wine, which gives me something to look forward to. Overall, it’s a triumph.

High protein, low calorie

Weight loss: 1st

Jo Hornblow, 46, is a financial administrator. She is divorced and lives near Cheltenham. She has four children — James, 20, Lottie, 18, Izzy, 13, and Charlie, 11.

The DNA test revealed I have a preference for sugary, fatty high calorie food so I was put on a higher protein, calorie restricted diet which was low in sugar and fat with 55 per cent carbohydrates, 25 per cent protein and 20 per cent fat.

Jo Hornblow, 46, (pictured before left and after right) dropped from 11st 8lb to 10st 8lb following a high protein, low calorie diet

Higher protein diets keep you fuller for longer and Ifound it easy to replace bad habits with good ones, such as having an apple and a handful of nuts as a treat instead of the contents of the biscuit barrel.

The trickiest part has been dieting on my own rather than having the camaraderie of a group. But it was interesting to learn I have a variation of the FTO gene, indicating a tendency to overeat. Discovering I’m at greater risk of type 2 diabetes and higher cholesterol has also motivated me to think about my health as well as my waistline.

Low fat, high carb

Weight loss: 9lb

Michelle Brooks, 47, is a medical sales rep, and lives in Glasgow. She is divorced with two children aged 19 and 15.

I thought this diet would be a revelation but it’s proved to be pretty hard, with a weight loss of 5lb in three months and no change in my dress size. I was told I have the MTIF3 gene variation, which gives a higher chance of having an increased body size, and another gene variation which reduces the levels of the fat-burning hormone.

Michelle Brooks, 47, (pictured before left and after right) from Glasgow went from 12st 10lb to 12st 1lb following a low fat, high carb diet plan

So I was put on a low-fat, high-carb diet. I’m apparently more sensitive to excess calorie intake. I was told I needed to keep my saturated fat intake to less than 10 per cent of my diet and stick to 60 per cent carbohydrates, 20 per cent protein and 20 per cent total fats. But I’ll be glad to see the back of the meal plans I was sent as I found them bland and limited.

In fact, I’m sick of toasted wholemeal bread for breakfast, pasta for lunch and carb-heavy veg. I also hurt my back midway through the diet so haven’t been able to exercise as much as I’d have liked — I discovered I need moderate exercise to compensate for lower levels of the fat burning hormone. But I’ve gone back to Slimming World now and I’ve lost an extra 4lb.

Low fat, low calorie

Weight loss: 9lb

Natasha Mockett, 39, is a chief financial officer and lives in Hampshire with her husband Nick, 40, a finance manager and their two children aged four and two.

My results indicated that if I eat more food than my body needs it will store the excess calories as fat, so I was given a low calorie, low fat diet.

I also have the variation of the ADIPOQ gene which reduces levels of the fat burning hormone, so I needed to cut out saturated fat and up the quantities of ‘good’ fats omega-3 and omega-6 by eating oily fish, avocado, walnuts and seeds.

Natasha Mockett, 39, (pictured before left and after right) from Hampshire shrunk from 10st 11lb to 10st 2lb

I stuck rigidly to the recommendation that I eat 1,300 calories a day made up of 60 per cent carbs and 20 per cent each of protein and fat. The weight loss was slow —it took four weeks to lose 5lbs. But when I switched the recommended four slices of bread for other healthy carbs the weight began to fall off.

I managed to drop down to 10st 1lb, but I lost track on a recent holiday and 3lb crept back on. I’m staggered at my soaring energy levels, clarity of thought and how I’ve finally stopped obsessing over food. I reckon I’ve finally cracked this weight loss lark by developing new habits for life.

Low fat, high omega-3

Weight gain: 3lb

Natalie White, 38, is a payroll clerk and lives in Lincoln with her husband Matthew, 35, an engineer, and their three children aged 17, six and two.

I don’t have the fat gene variation linked to increased appetite, but the tests did show my body’s ability to burn fat is low and I’m predisposed to high cholesterol. So I was given a low fat diet which was high in omega 3 to keep my cholesterol in a good range.

Natalie White, 38, (pictured before left and after right) from Lincoln gained 3lbs as she struggled to follow a low fat, high omega-3 regime going from 12st 5lb to 12st 8lb

This has meant lots of rice, fish and chicken but no eggs — which I love. I was allowed four slices of bread a day but this didn’t help to fill me up as the meal portions were very small, leaving me feeling hungry and dissatisfied. This meant at weekends I’ve consistently fallen off the wagon, tucking into cheese and also takeaways.

I’ve also felt exhausted all the time, which I’m sure is down to the portion sizes. Overall, this isn’t the diet for me and although I initially lost 10lb, it has crept back on.

However, I am now a dress size smaller than when I started. Long-term, I think calorie counting works better for me, as that way I can legitimately incorporate some of the naughty high fat foods that I often fancy.

High protein, low fat

Weight loss: 1st 13lb

Sam Mercer, 46, is a civil servant and lives in Kent with her partner Steve, 51, who works in retail, and her four children aged 22, 19, 12, and seven.

Sam Mercer, 46, (pictured before left and right) from Kent dropped from 14st 2lb to 12st 3lb following a high protein, low fat diet

I discovered I have a variation of the FTO gene which significantly increases appetite and a tendency to overeat.

It means my brain gets stimulated upon seeing high energy food and it can increase appetite stimulant hormones. So to counter that, my diet plan was very simple, bland and repetitive.

But it’s really worked for me to have porridge every day for breakfast, a chicken salad or sandwich for lunch, and an evening meal of fish or poultry with rice. But I haven’t banned anything.

I had chocolate at Easter and we’ve been out for dinner a few times. I’ve always been the queen of crash diets, losing loads of weight quickly, so it’s been a big adjustment to follow a sensible diet that’s about perseverance, steady weight loss and a change in lifestyle. I ’m determined to continue with the good habits I’ve learned.